The fastest-growing and largest minority group in the United States, Latino immigrants accounted for 16% of the nation's population in 2010 and are projected to represent 30% by 2050.1,2 Latino children age 5 or under, and those of Mexican origin, in low-income families or in rural locations, have the highest rates of early childhood caries of any racial/ethnic groups, second only to Native Americans.3-7 Latinos have one of the lowest dental utilization rates of all ethnic/racial groups, with Mexican-Americans having the lowest utilization rate of all Latino groups.8-10 Maintaining oral health requires the ability to understand and act on health information and to navigate dental healthcare; in other words, an adequate level of Oral Health Literacy (OHL).11,12 Addressing OHL in Mexican immigrant families with appropriately framed education in contexts where they feel safe and respected, such as English as a Second Language (ESL) classes, is an emerging dental public health priority.13,14 ESL classes present an ideal environment to promote OHL to newly arrived immigrant parents and families at high risk for dental caries, particularly due to the well-established safe and trusting reputation of ESL classroom environments.16-18 Prior to developing OHL curriculum for use in ESL classes serving Latinos, it is first necessary to understand what exactly constitutes OHL in this population. What are current understandings of oral disease prevention, sources of and access to oral health information, experiences with and ability to use oral health information to access professional dental care, and understandings and perceptions of dental health services? We propose to conduct ethnographic research to investigate these questions which underpin oral health disparities among Mexican immigrant families. The proposed study is the first and vital formative stage of a research program focused on oral health disparities and OHL. It will provide the foundation for the development of appropriately framed core OHL curriculum aimed at assisting Mexican immigrants to better navigate the dental care system. We will evaluate foundational items of this curriculum in ESL classes in order to refine it for the next stage of research. The overall goal of the currently proposed formative study is to establish the foundation for an intervention to enhance dental system understanding and navigational (OHL) skills among Latino immigrant parents and families. The Specific Aims are to 1) Define the dimensions of OHL for SF Bay Area Mexican immigrants (i.e. conduct ethnographic research - observations, individual and group interviews - to describe experiences of oral health disparities, existing oral health understandings and system navigation); and 2) Develop foundational items for an OHL curriculum for delivery in ESL catchment areas and settings (present foundational items in ten (10) ESL classes serving Mexican immigrants; observe their engagement with these foundational aspects of a future curriculum and conduct 10 group interviews with adult ESL students for their views about each item).